Currently, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, and the like are used as commercial secondary batteries. Among them, lithium secondary batteries have little to no memory effect in comparison with nickel-based secondary batteries, and thus lithium secondary batteries are gaining a lot of attention for their advantages of free charging or discharging, low self-discharging, and high energy density.
A lithium secondary battery generally uses lithium oxide and carbonaceous material as a positive electrode active material and negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate respectively coated with the positive electrode active material and the negative electrode active material are disposed with a separator being interposed between them, and an exterior, namely a battery case, which seals and accommodates the electrode assembly together with an electrolyte.
Generally, a lithium secondary battery may be classified into a can-type secondary battery where the electrode assembly is included in a metal can and a pouch-type battery where the electrode assembly is included in a pouch of an aluminum laminate sheet, depending on the shape of the exterior.
Recently, secondary batteries are widely used not only for small-sized devices such as cellular phones but also middle-sized or large-sized devices such as vehicles and power storages. When being used for middle-sized or large-sized devices, a great number of secondary batteries are electrically connected to enhance capacity and output. In particular, in middle-sized or large-sized devices, pouch-type secondary batteries are frequently used since they can be easily stacked and have light weight.
However, a pouch-type secondary battery does not have great mechanical rigidity and may not easily maintain its stacked state by itself since it is generally packaged with a battery case made of a laminate sheet of aluminum and polymer. Therefore, when configuring a battery module including a plurality of pouch-type secondary batteries, a cartridge is frequently used to protect the secondary batteries from external impacts or the like, prevent fluctuation of the secondary batteries and facilitate easier stacking of the secondary batteries.
The cartridge frequently has a tetragonal plate shape with a hollow center, and at this time four sides are provided to surround the outer circumference of the pouch-type secondary battery. In addition, a plurality of cartridges may be stacked to configure a battery module, and a secondary battery may be located in a vacuum space formed among the stacked cartridge.
Generally, a battery pack is frequently cooled in various ways, for example direct or indirect water or air cooling. In particular, in case of an existing battery pack, in order to remove heat emitted during a charging or discharging process, a plurality of cooling members made of metal material is disposed around a secondary battery, and a cooling medium such as air or water is supplied around the cooling member. For example, in an existing technique, in many cases, a metallic cooling member such as a cell cover or a cooling plate for the flow or thermal conduction of the cooling medium is interposed between secondary batteries.
However, if the cooling member or a channel for the flow of a cooling medium is provided between secondary batteries, the battery module inevitably has increased volume and weight as a whole and also has a complicated structure. Therefore, the battery module has deteriorated efficiency in fabrication, also has a limit in miniaturization, and also has an increased fabrication time and cost.
Further, since the cooling member is generally made of electrically-conductive metal, when a cooling member is provided to the battery module, insulation against a battery cell should be put into consideration. Therefore, the battery module may have more complicated structure due to a configuration for the insulation, and its volume and cost may also be increased.